Yes, Boris Johnson has fibbed and philandered. But what has he actually done wrong?

I’m trying to imagine the BBC’s Eddie Mair interviewing Nelson Mandela, the elderly African squirming uncomfortably in his seat as Mair, like one of the late Eugene Terre’Blanche’s famous Dobermans, snarls ever more menacingly, foam dripping from his bared gums.

‘So, in 1961, with several others, you founded a vicious terrorist movement, Spear of the Nation, carried out bombing after bombing and pledged that if these tactics failed you would resort to guerrilla warfare and terrorism…’

Mandela looks askance: ‘Excuse me, I thought this was that programme where you choose records and a book…’

Mair shakes his head, face wreathed in disgust. ‘Pretty nasty piece of work, aren’t you?’ Mandela, evidently confused, says that he would like to take with him Althea and Donna’s late 1970s hit, ‘Uptown Top Ranking’, and can he go now, please?

It isn’t going to happen, of course. That sort of interviewing is reserved, on the BBC, for people from the political right, such as the mayor of London, Boris Johnson. You will never hear a BBC interviewer (except Humphrys, perhaps) stick the boot into a leftie like that, unless it’s lefties who don’t matter, like George Galloway.

The comment ‘pretty nasty piece of work’, addressed to a cosmetically ruffled Boris, was the moment that personal and political antipathy was allowed to spill into what was, otherwise, a perfectly decent interview. For Eddie Mair is without doubt a good presenter and interviewer. But have you ever heard the BBC attack Ed Balls, for example, in such a personal manner, with the presenter’s distaste clearly evident? And Ed is commonly regarded as being a ‘nasty piece of work’, (although he’s always been perfectly nice to me on the rare occasions we’ve met).

This was Boris week on the Beeb, where they decided that as they’d missed Savile, they may as well stick it to another monster before he gets to be prime minister.